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01 June 2004

Tiny science thinks big

Nanotechnology is growing, building for the future.

By Ellen Fussell

Sunscreen using nanodispersed zinc oxide, antiwrinkle cream incorporating vitamin A inside a polymer capsule, tennis balls made with clay polymer nanocomposites to increase bounce, and stain-resistant clothing—these are just some of the consumer by-products of nanotechnology. While nanotechnology is burgeoning on the consumer side, it's also making a splash with nanomaterials in automotive applications, nanoelectronics and devices, and nanobiomedical applications. And the possibilities seem endless, say the technology's proponents.

The government is putting close to $3 billion a year into nanotechnology, said Sujeet Chand, senior vice president and chief technology officer, Rockwell Automation, Milwaukee, Wis. The Institute of Soldier Nanotechnologies at the Massachusetts Institute of Technology is looking at a nanosuit for soldiers that could sense and analyze body fluids and determine what kind of medication to give a solider to monitor vital signs. "On top of that, venture capital funding is around $1 billion a year in nano-start-ups," he said. "So in total you have roughly $4 billion a year going into nanotechnology research."

Nanomaterials

Nanomaterials are perhaps the most mature of applications, Chand said. Nanomaterials, when added to regular material, can improve its strength and resistance to environmental pollutants. "We're looking at using nanomaterials in a lot of our internal products," Chand said. "If we can improve the properties of lubricants like grease with nanomaterial or particle additives, that would make a big difference in electric motors. It would affect parts on circuit breakers that can improve properties," he said.

Nanomaterials include nanoparticles in composites or material such as carbon nanotubes. A nanotube is a carbon-based cylinder that conducts electricity well. "With 100 times the tensile strength of steel, thermal conductivity better than all but the purest diamond, and electrical conductivity similar to copper, but with the ability to carry much higher currents," carbon nanotubes are the latest and greatest material on the nanotechnology horizon, said a January 2003 CMP/Científica white paper on nanotubes.

One application includes a television with carbon nanotubes in the display instead of liquid crystal displays (LCDs) used in today's flat-screen TVs and computer monitors. A Forbes/Wolfe 2003 nanotech product guide explained how organic light emitting diodes (OLEDs) are much brighter than LCDs. They also don't require backlighting.

In another application, General Motors uses composite material for the running boards of its Astro and Safari minivans. The theory is durable composites with nanoparticles could increase fuel efficiency. General Motors is also now using a lightweight, high-performance nanocomposite material in the body of side molding of the 2004 Chevrolet Impala, GM's highest volume car, said a January 2004 GM press release. The nanocomposite application provides a 7% weight savings of the body side moldings per vehicle and improved surface quality. GM uses nearly 540,000 pounds of nanocomposite material per year—the highest volume of olefin-based nanocomposite material use in the world.

The National Science Foundation estimated nanotechnology applications may be worth more than $1 trillion in the global economy in the next ten years or a little more. The nanocomposite material used in the GM vehicles is the result of research at the GM Research & Development Center in Warren, Mich. and an exclusive GM development agreement with Bassell, a producer of polypropylene resins for plastics and southern Clay Product, Inc., a nanoclay supplier out of Gonzales, Texas.

Jihui Yang of the Materials and Process lab at General Motors in Warren, Mich., explained the benefits of lower-cost carbon nanotubes in a 2003 National Science Foundation presentation. Yang said this new class of materials is made of nanocomposites whose distinguishing factors include a filler size on the molecular scale. A nanofiller equals the size of a fingernail; a talc is comparable to an 18-inch beach ball; and glass fiber is 1 mile long and 5 feet in diameter. When you add electrical conductivity to polymer composites (closures and tires for example), you see static dissipation (electrokinetic phenomena, lightning strikes, and high-voltage wires), electromagnetic compatibility (reduction in measured equation of invariance), and enhanced thermal conductivity, Yang said.

One challenge is replacing current methods in automotive applications, such as cladding and facias, with nanocomposites, Yang said. An ongoing challenge is getting high-volume use. There's a growing need to get the cost down, both for structural applications and for hybrid-electric-vehicle battery applications, Yang said in his presentation. Nanomaterials of interest to the automotive community include thermoelectrics (grown using nanotemplates and nanostructures such as clathrates and skutterudites), nanocrystalline metals for superplastic forming and high strength, nanocatalysts to reduce unwanted engine emissions and fuel-cell catalysts, and tribology and surface films.

In terms of manufacturing nanomaterials, "as we see more and more applications of nanoadditives to create composites, we're really interested in the control and automation of that whole process," Chand said. "The nanoadditives will be in very small quantities, and you want to make sure that any reaction you're hoping for with an additive is occurring. You have to control the process with certain temperatures or pressure constraints to ensure quality of composite material."

Nanoelectronics and devices

An example of nanoelectronics is computing memory to replace processors and memory in the next ten to twelve years. Nanoelectronics will possibly break the constraints of Moore's Law, Chand said. Moore's Law is based on the 1965 observation of Gordon Moore, co-founder of Intel, that the number of transistors per square inch on integrated circuits had doubled every year since their invention. Moore predicted this trend would continue for the foreseeable future, but the pace has slowed in the past few years. Yet data density has doubled approximately every eighteen months. "There's some speculation we're hitting the limits on Moore's Law," Chand said. "As you continue to drive improvements in processing power and reach limitations in how many transistors you can put on a square millimeter of silicon, if you switch to the bottom-up approach, the nanotechnology, where you manipulate at the atomic level, you can create electronics significantly faster than the current top-down approach," he said.

Bio applications

A slew of drug companies are investing heavily in drug delivery mechanisms based on nanotechnology. "If you have a tumor you want to deliver medication to, the nanocarrier of the medications will identify the tumor and focus on delivering medication just to that tumor," said Dr. Ram Pai, Rockwell's director for advanced technology and researcher for nanotechnology applications.

"They have taken a nanoparticle that could be attached to another particle that might have certain properties. Several drug companies around the world are pursuing this technology and are using it to inhibit tumor growth or to encourage growth of blood vessels," Pai said.

Manufacturing sector

Eventually it will come back to how you manufacture these drugs. How do you mass produce these drugs? With the exception of carbon nanotubes, none of the other areas are into mass production yet. "We're several years away from mass producing nanomedications or nanodevices," Pai said. "So from Rockwell's perspective, we believe this is an exciting technology with investment that's going into the R&D community."

Pai said the industry also needs tools to incorporate in nanoproduction—tools for stimulating and modeling and looking at the nanoparticles, which are between 1 and 100 nanometers. The element of light is 400 nanometers. "You can't see these particles," he said. "So the industry will need tools for it, and they'll need standards to go with these tools."

Nanostandards

Currently the Institute of Electrical and Electronics Engineers (IEEE) is developing standards to establish fundamental nanotechnology platforms that support the growth sector. One standard is IEEE P1650, "Standards Test Methods for Measurement of Electrical Properties of Carbon Nanotubes." When it is complete, it will be the first standard to define electrical testing procedures and to suggest characterization tools for carbon nanotubes, said an IEEE Standards news release. "IEEE is taking a leadership role to work in the areas of nano as late as November of last year," Pai said. He believes developing the nanotechnology tools and standards should evolve in tandem. "It should all occur hand in hand," he said. With the invention of electric motors eighty years ago, "they replaced belts and pulleys off these shafts to make parts. But then they developed standards and tools; there were new ways to use electrical energy, plugs and sockets to connect. And they needed standards," Pai said. "Nanotechnology will follow a similar methodology, and we'll need manufacturing techniques and standards."